The elements belonging to groups _______ are known as 'd' block elements.
- A.3 to 12
- B.1 and 2
- C.13 to 18
- D.3 to 10
Correct answer
Explanation
The correct answer is A, 3 to 12. The d-block occupies the middle of the modern periodic table, groups 3 to 12, and its members are also called transition elements. In these elements the last electron enters a d orbital of the second-last shell, which is why they show variable valency, form coloured compounds and work as good catalysts. Iron, copper, zinc, silver, gold and mercury all belong here. The block has four series, filling the 3d, 4d, 5d and 6d orbitals, one in each of periods 4 to 7. B is wrong because groups 1 and 2 are the s-block, the alkali and alkaline earth metals. C is wrong because groups 13 to 18 form the p-block, which holds most non-metals and the noble gases. D is wrong because the d-block does not stop at group 10; zinc, cadmium and mercury in group 12 are part of it. Exam tip: s-block = groups 1 and 2, d-block = groups 3 to 12, p-block = groups 13 to 18, f-block = lanthanides and actinides placed below the table.
Practice Questions
View allThe fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by
- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
Show answer
In 1609 Kepler showed that the planets move around the Sun in elliptical orbits, with the Sun at one focus of the ellipse.
Read the full explanation →Which one of the following statements is correct?
- A.Urea is produced in liver.
- B.Urea is produced in blood.
- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
Show answer
Liver cells turn the toxic ammonia released from the breakdown of amino acids into urea through the ornithine cycle, also called the urea cycle.
Read the full explanation →Which one of the following is the correct sequence of passage of light in a compound microscope?
- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
Show answer
Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.
Read the full explanation →Which one of the following statements regarding haemoglobin is correct?
- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
- B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
Show answer
It binds oxygen at its iron-containing haem groups and carries some carbon dioxide on its protein chains. Each haemoglobin molecule has four polypeptide chains and four haem groups, and each haem iron can hold one oxygen molecule, forming oxyhaemoglobin in the lungs.
Read the full explanation →Which one of the following statements regarding histone proteins is correct?
- A.Histones are proteins that are present in mitochondrial membrane.
- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
Show answer
They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.
Read the full explanation →